KR101232952B1 - Signaling mimo allocations - Google Patents

Abstract

The present invention relates to demodulation of radio signals from a base station having collocated transmit antennas, and more particularly to signaling allocation information from a base station to a mobile terminal. The allocation information may include timeslot and code information of allocation to other mobile terminals. Some embodiments of the present invention facilitate a mobile terminal's ability to receive and demodulate a signal containing multiple interfering signals by communicating codes allocated to other mobile terminals.

Description

Method and apparatus for signaling MIO allocation {SIGNALING MIMO ALLOCATIONS}

The present invention relates to wireless signal processing in a CDMA system, and more particularly to signaling assignment information including which code in which timeslot to assign to the mobile terminal.

A cellular wireless system or network may include multiple base stations and multiple mobile terminals. The base station may be referred to as Node B. A mobile terminal may also be referred to as a mobile, mobile radio, mobile transceiver or user equipment (UE). The mobile terminal can be fixed, stationary, portable, removable and / or mobile within or between cells. A single base station can provide services to multiple mobile terminals by transmitting separable transmissions to each mobile terminal. The mobile terminal can determine which signal is instructed to itself and can separate this signal from the signal directed to the other mobile terminal.

The signal can be separated into one or more regions. For example, the signal may be separated in the time domain by transmitting a time division multiple access (TDMA) modulated signal. Additionally, the signal can be separated in the frequency domain by transmitting a frequency division multiple access (FDMA) modulated signal. The signal may be separated in the code domain by transmitting a code division multiple access (CDMA) modulated signal. The signal can be separated in the spatial domain by transmitting the signal from the array antenna. The cellular wireless system may apply a combination of these and / or other separation techniques.

In a CDMA system, spread spectrum technology can support multiple users. In a direct sequence CDMA system, data payloads are encoded using codes that can be orthogonal or pseudo-orthogonal to other codes. The mobile terminal can receive the CDMA modulated signal and can perform various demodulation operations, such as matched filtering, using one or more codes assigned to the mobile terminal.

When the base station modulates and transmits a coded CDMA signal using a particular code, the mobile terminal can use the match filter and the specific code assigned to that match filter to generate a high output from the match field. A matched filter using a particular code will produce a low output for signals directed to different mobile terminals assigned different codes. As a result, the mobile terminal decodes only the signal directed to it using the output of the high matched filter. Similarly, the mobile terminal uses a low matched filter output to reject signals that are probably directed towards other mobile terminals.

Typically, a direct sequence CDMA system uses either a frequency division multiple access (FDD) scheme or a time division multiple access (TDD) scheme. In an FDD system, communication between a mobile terminal and a base station occurs in two non-overlapping frequency bands. In a TDD system, communication between a mobile terminal and a base station can occur within a single frequency range. In either case, the data payload is transmitted between the mobile terminal and the base station. Uplink data or uplink traffic is transmitted from the mobile terminal to the base station. Downlink data or downlink traffic is transmitted from the base station to the mobile terminal.

In FDD systems, frequency separation is applied. Uplink traffic is sent at one center frequency and downlink traffic is sent at another center frequency. Uplink and downlink can operate simultaneously. In other words, while the mobile terminal transmits data to the base station on the uplink, the base station can transmit data to the mobile terminal on the downlink. Frequency separation in the FDD system ensures that the uplink does not interfere with the downlink.

In contrast, the TDD system employs temporary separation. The TDD system can transmit uplink and downlink data within a single frequency range, but at different times. The air interface link between the base station and the mobile terminal group in the TDD cell may be configured in the time domain as a sequence of frames. Each frame may be arranged in a set of time slots. Other time slots may be allocated for downlink traffic while some time slots are allocated for uplink traffic. Each time slot can be further subdivided in the code domain using a code set. Data is separated from the code set into codes having different orthogonal or pseudo orthogonal codes. To facilitate decoding, the data transmitted through the code is separated into data payloads, training sequences and guard intervals encoded using different orthogonal or pseudo orthogonal codes; The resulting structure of the data payload, training sequence and guard intervals is referred to as a burst.

To implement spatial diversity, the TDD base station may use two or more antennas. During the downlink time slot, the first set of bursts transmitted during the time slots via the first antenna may be directed towards the first group of mobile terminals and the second set of bursts transmitted during the same time slot via the second antenna may be It may be directed towards the second group of mobile terminals. The first and second groups of mobile terminals may include the same and / or different mobile terminals.

The base station may assign a group to one or more codes from one or more time slots of the frame for downlink traffic. Assignment may be performed for the first mobile terminal. The mobile terminal can receive data at a high rate using each additional code of the time slot assigned to it. Moreover, the base station can make this assignment to time slots that issue simultaneously, each time slot being transmitted simultaneously through different antennas. The base station notifies each mobile terminal that it will receive downlink data by advertising the time slot and code assigned to the mobile terminal. The mobile terminal then monitors the time slots and decodes the signal using the code assigned to that mobile terminal.

1 shows an exemplary frame structure of a TDD cellular wireless network. A single TDD radio frame 100 includes 15 time slots (time slots 1-15). Each time slot includes a set of bursts, which may have up to 16 valid code signals using codes 1-16. The base station transmits zero, one or more bursts using one or more code signals included in each burst (via the downlink). Similarly, one or more mobile terminals each transmit zero, one or more bursts on the uplink, each burst containing one or more code signals. A separate burst on the uplink may be received by the base station as a single combined set of bursts.

The network may split the frame into downlink time slots 101 and uplink time slots 102. The network may split the downlink and uplink time slots symmetrically when transmitting the same amount of data received by the mobile terminal. If the majority of the data flows in one direction, the network can form an asymmetric service. For example, Internet traffic typically occupies a greater amount of downlink data than uplink data.

Frame 100 is configured to have ten downlink time slots (time slots 1-10) 101 and five uplink time slots (time slots 11-15) 102. Assignment information for three mobile terminals (terminals 1 to 3) is also shown. The network assigns terminal 1 codes (codes 3 to 6) of a single time slot (time slot 3). These four codes are not shared with other mobile terminals. Similarly, terminal 1 does not experience intracell interference because the time slots occur so as not to be shared with other mobile terminals and no code is used for the immediately or immediately after time slots.

The network assigns six codes to terminal 2, that is, codes 2 and 3 in time slots 5-7, respectively. The network assigns eight codes to terminal 3, that is, codes 6 and 7 in time slots 5-8, respectively. Since signals sent to terminals 2 and 3 are multiplexed in each of time slots 5, 6, and 7, the signals in these time slots directed to one mobile terminal can interfere with the signal directed to the other mobile terminal. Since time slot 8 is not code multiplexed with other terminals except terminal 3, terminal 3 does not receive interference from other codes in time slot 8.

Exemplary TDD time slot bursts may include multiple code signals. Each burst may be considered to contain three parts (data payload, training sequence and guard interval). Although the order and size of these portions within the burst may vary from system to system, typically the training sequence will be inserted as a midamble between two halves of the data payload. Alternatively, the training sequence may be located in the head (preamble) or tail (postamble) of the data payload. In addition, the guard interval will typically add to the end and / or timing of the data payload and training sequence.

2 shows a segment of a TDD code signal 200 from a single burst of one time slot. The code signal 200 comprises a data payload (part 1) 201 followed by a midamble training sequence 202 followed by a remainder (part 2) 203 of the data payload and a guard interval 204. This follows. The data payload 201, 203, training sequence 202, and guard interval 204 may be used in a cellular wireless network, such as the UTRA TDD mode, as defined by the third generation partnership project (3GPP).

In each time slot, a set of bursts can be transmitted, and the burst contains one code signal per valid code. Each code signal may include a unique training sequence or may include a training sequence used by one or more other code signals. The set of bursts may be distorted by the propagation environment operating in a cellular wireless system. The propagation environment can provide multiple paths between the base station antenna and the mobile terminal antenna. The resulting radio channel may not be an accurate channel but rather a channel that combines delayed versions of the transmitted signal. For example, a signal transmitted from a base station and directed towards a mobile terminal may have multiple paths and these signal paths may have different lengths. Thus, the burst or signal may reach the mobile terminal as multiple replicas of the transmitted signal and each replica may arrive at different times by paths of different lengths. In this way, sequences of symbols in a signal can destructively interfere with each other.

For example, a transmitted signal traveling a short path first arrives at the receiver. An equally transmitted signal traveling a long path may appear at the receiver as a delayed version of the first received signal. Therefore, the first symbol traveling a long path may reach the receiver at the same time that the subsequent symbol traveling a short path arrives at the receiver. The mobile terminal can receive a signal comprising a combination of one or more delayed versions of the transmitted signal. This symbol overlap is known as intersymbol interference and may be due to multipath propagation.

Intersymbol interference due to multipath propagation also reduces orthogonality between signals with different codes. Loss of orthogonality between the codes degrades the correlation and degrades the overall system performance. Moreover, intersymbol interference can increase the interference experienced by two signals transmitted in the same time slot and having different codes.

For example, referring to FIG. 1, intersymbol interference may cause loss of orthogonality between codes 2, 3, 6 and 7 indicated in terminals 2 and 3 in time slots 5, 6 and 7, respectively. In addition, intersymbol interference can cause loss of orthogonality between codes 6 and 7 of terminal 3 in time slot 8. If the network does not employ mitigation techniques that reduce the effects of multipath, the performance of the system will be degraded.

The receiver of the mobile terminal may receive a signal including traffic directed to both itself and the other mobile terminal. The receiver of the mobile terminal uses the code assigned to it to extract data directed only to it. Encoded data directed to different mobile terminals in the same time slot from the same or different antennas may interfere with the reception and data extraction of the mobile terminal. The base station can increase the transmit power to compensate for and overcome the sensed interference. However, increasing transmit power also increases interference in the network. Therefore, other means of processing the interfering signal may be useful.

Some embodiments of the present invention facilitate the mobile terminal's ability to receive and demodulate a signal comprising multiple interference signals. The base station may transmit allocation information of another mobile terminal to the mobile terminal. The allocation information may include time slot and code allocation information of another mobile terminal.

According to a first aspect of the invention, a method is provided for delivering code assignment according to claim 1.

According to a second aspect of the invention, a method is provided for delivering code assignment according to claim 7.

According to a third aspect of the invention, a method is provided for compiling an allocation table according to claim 21.

According to a fourth aspect of the invention, a method is provided for compiling an allocation table according to claim 26.

According to a fifth aspect of the invention, there is provided an apparatus for conveying code assignments according to claim 27.

Other features and aspects of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate by way of example the features according to embodiments of the invention. The scope of the invention is not intended to be limited to this summary, but is to be defined only by the claims set forth below.

1 shows an exemplary frame structure of a TDD cellular wireless network.

2 shows a segment of a TDD code signal from a single burst of one time slot.

Figure 3 shows an example of the output signal of the midamble detector of the receiver.

4 shows resource allocation information implicitly delivered to each mobile terminal receiving an assignment.

5 shows a time and flow chart of HSDPA transmission.

6 shows allocation messages for three mobile terminals.

7 shows a base station delivering assignment information to two mobile terminals.

8 shows an example of broadcasting resource allocation information in a frame.

9 shows separate code channels transmitted from two antennas.

10 shows a separate code channel transmitted from two antennas.

In the following description, reference is made to the accompanying drawings that illustrate various embodiments of the invention. It is to be understood that other embodiments may be utilized and that mechanical, structural, structural, electrical, and operational changes may be made without departing from the spirit and scope of the present disclosure. The scope of the embodiments of the present invention is defined only by the scope of the issued patents, without limiting the meaning to the detailed description below.

Portions of the detailed description below may be represented by procedures, steps, logic blocks, processing, and other symbolic representations of data bit operations that may be performed in computer memory. Procedures, computer-implemented steps, logic blocks, processes, etc., are herein represented by a self-consistent sequence of steps or instructions that drive the desired signal. The step is to utilize the physical manipulation of the physical quantities. This physical quantity can take the form of a radio signal that can be stored, transmitted, combined, compared, manipulated, etc. in an electrical, magnetic, or computer system. These signals may be referred to as bits, values, elements, symbols, characters, clauses, numbers, etc. in time. Each step can be performed by hardware, software, firmware, or a combination thereof.

Various embodiments of the present invention will be described below in connection with the recommendations and specifications of the 3GPP UTRA TDD system. However, this embodiment is generally applicable to other mobile wireless and cellular systems. Again, for example, an application filed pending May 4, 2004, entitled “Midamble Allocation for MIMO Transmission” (Agent Document Control Number 562493000300), incorporated herein by reference. do.

To increase overall system performance, the system may employ mitigation techniques to compensate for the loss of orthogonality between the codes. Mitigation techniques may reduce the effects of interference between signals in time slots using code separation. Serial interference cancellation is an example of a mitigation technique applied to FDD systems. Multi-user detectors (MUDs) are examples of mitigation techniques applied to TDD systems.

The receiver employing the MUD circuit jointly decodes the transmission directed to the multiple mobile terminals. By receiving and decoding signals directed to other receivers, the MUD circuit can eliminate interference due to unnecessary signals. This unnecessary signal is a signal transmitted by a base station and received by one mobile terminal but may be a signal directed to another mobile terminal.

The receiver MUD circuit or other mitigation circuitry may use the allocation information to improve the signal quality of the signal directed to the mobile terminal. The allocation information may include information about the code, time slots, antennas, and signals for other mobile terminals and may include information about the base stations to which they are assigned. The allocation information may include information about transmission of the current cell and / or information about transmission of one or more neighboring cells. The mobile terminal can use the allocation information to help decode the burst of payload data directed to it.

Space diversity can be another technique for improving system performance. The transmitter and / or receiver may use multiple antennas. Transmit diversity can be applied by transmitting from two or more antennas at the base station. Transmitters that transmit signals through one or more antennas may be referred to as multi-antenna transmitters. Transmit diversity can assist the receiver by providing multiple copies over different channels of the same transmit signal. If severe deterioration occurs in the first channel from the first transmit antenna, the signal from the second transmit antenna traveling through the second channel can reach the receiver intact.

In conventional transmit diversity systems, generally the same data may be transmitted from multiple antennas, ie from one or more transmit antennas. According to some embodiments of the present invention, a multi-antenna transmitter may transmit different signals for each antenna during one or more time slots. For example, a transmitter with two antennas may transmit a common signal through both antennas while transmitting a group of bursts during the first sequence of time slots. Alternatively, during the first sequence of time slots, the transmitter may transmit a signal through the first antenna and no signal through the second antenna. Then, during the second sequence of time slots, the transmitter may transmit two different signals and one unique signal through each antenna.

In a receive diversity system, a mobile terminal can be equipped with multiple receive antennas. Receivers that receive signals via one or more antennas may be referred to as multi-antenna receivers. The first received signal from the first receive antenna and the second received signal from the second receive antenna may be processed to elicit a first and second set of transmitted signals. For example, the receiver may use the characteristics of the channel and code convolution from each receive antenna to determine the signal transmitted from each transmit antenna.

A system having a transmitter using multiple antennas having multiple antennas to transmit a signal corresponding to the receiver may be referred to as a multiple input / output (MIMO) system. If the transmit antennas are sufficiently spatially separated (e.g., greater than half-wavelength), and the receive antennas are spatially sufficiently separated, the path formed between each transmit / receive antenna pair may be a channel that does not correlate with the type of fading.

A system having spatially separated multiple transmit antennas, spatially separated multiple receive antennas, or spatially separated multiple transmit and receive antennas, such as a MIMO system, may provide a unique channel between each transmit / receive antenna pair. Although one channel temporarily provides a fault signal to the receiver (eg, due to propagation conditions causing the path to fade), it is unlikely that all channels formed by each transmit / receive antenna pair will fail simultaneously. As long as there is at least one acceptable channel between one transmit antenna and one receive antenna, the receiver can decode the transmitted signal.

The signal received from a particular transmit antenna may have a unique signature by the convolution of the code used to transmit that signal and channel. If the channel from each antenna is not correlated, this signature may allow the transmitter to transmit different information from each transmit antenna using the same code. For example, the transmitter may transmit a first set of bursts having a set of signals encoded corresponding to the first set of codes over a first transmit antenna in a particular time slot. The transmitter may transmit a second set of bursts having a set of encoded signals using a portion of the first set of identical codes over a second transmit antenna in the same time slot.

By using spatial diversity and MIMO modulation and demodulation techniques, the system can increase throughput by transmitting different signals through an array of transmit antennas. This increased throughput is due to an increase in the number of transmit and receive antennas, thereby increasing the effective number of codes available in the time slots being transmitted simultaneously.

Interference from other codes in the same time slot, delayed symbols from multipath channels, bursts from a second antenna of a multi-antenna transmitter, and bursts from neighboring cells increase the need to actively apply mitigation techniques. Reduce the adverse effects of these signals.

For the purpose of eliminating interference and unwanted signals destined for other terminals, it may be helpful for the receiver to know the presence of these unwanted signals and to know which code has encoded these unwanted signals. Detection of unwanted signals can be performed with digital signal processing techniques. Alternatively, the presence of one or more code signals directed to one or more other mobile terminals may be communicated to the mobile terminal.

The receiver may use signal processing techniques to determine which midamble was transmitted. For example, the correlator may be used at the receiver to compare the received signal with a set of possible known training sequences. The correlator can generate a signal having peaks at various locations. The peak may estimate the channel formed between the transmitting antenna and the receiving antenna or express the characteristics of the channel. The location of these peaks may indicate which midamble was transmitted.

The transmitter may select and transmit a set of midambles to indicate a particular configuration of code used to encode data payload information. Once the receiver expects the set of midambles transmitted by the transmitter, the receiver can use the midamble to determine the set of codes used to encode the data payload information. The default midamble allocation scheme may be used to map the received midamble to a set of codes possibly used in the received time slots.

3 shows an example of the output signal 300 of the midamble detector of the receiver. In the output signal 300 of the midamble detector the receiver allows to determine a valid code that determines which code is valid. For example, the codes associated with peaks 1, 3, 4, and 6 are shown to have peaks above threshold 310, so the codes associated with these midambles are valid. The mobile terminal may also use the output of the midamble detector to estimate or represent the channel formed between the transmit and receive antennas. Channel estimation from this signal can be used to decode other signals in time slots where different codes are used.

The midamble can be used to relay information. The specific midamble may be used by the base station to indicate a valid code for the receiver group of the mobile terminal. Different midambles can be used to represent different groups of valid codes. The mobile terminal can determine which midamble has been transmitted, so as to infer which code is present in the time slot for the other mobile terminal.

Efficiently mapping the midamble or mapping to the code used may be referred to as the default midamble allocation scheme. An example of the default midamble allocation scheme is described in 3GPP document 3GPP TS 25.221, entitled "Mapping of Transport Channels over Physical Channels and Physical Channels (TDD)". If the base station uses the default midamble allocation scheme, the midamble is selected to allow the mobile terminal to determine which code is transmitted by the base station.

The base station can select the midamble to encode a number indicating the number of valid codes transmitted in the time slot by the base station. The base station provides a one-to-one mapping between the number of midambles used and the number of codes used.

The base station may signal a message indicating the total number of different midambles used in the time slot (to the mobile terminal). In addition, the midamble may be received as a peak at the receiver. Each midamble may be associated with one or more valid codes. Therefore, the number of valid codes in the time slot may be larger than the number of midambles used in the time slot. In this case, the mobile terminal may perform some additional signal processing to determine which portion of the code associated with the midamble is valid.

For example, if the base station signals a signal that eight midambles are used (UTRA TDD K _cell = 8) and the midamble detector of the mobile terminal detects peak 6 corresponding to the midamble 6, then the mobile terminal is a midamble. Additional signal processing may be applied to determine which code related to 6 was actually transmitted.

The midamble may designate one code and / or another code to be transmitted. In 3.84 Mcps UTRA TDD mode, midamble 6 relates to codes 7 and 8 when K _cell = 8 is used. Additional processing at the mobile terminal may determine whether only code 7 was transmitted, only code 8 was transmitted, or both code 7 and code 8 were transmitted. Once the mobile terminal deduces which code is valid, it can establish an interference mitigation function based on the information of this valid code. For example, the mobile terminal can supply a list of codes determined to be valid for the MUD circuit.

The cellular network can establish the maximum number of midambles available by balancing the benefits and drawbacks of the increased number of midambles. The increased number of midambles allows the base station to encode more types of code allocation schemes. In other words, by sending more unique midambles, the network allows the mobile terminal to calculate a valid code in more detail. However, the increased number of midambles also increases the noise on the receiver. In addition, channel estimation has a higher noise value and includes a shorter duration. In contrast, by transmitting fewer unique midambles, the receiver can make better channel estimation.

To perform improved interference mitigation, the TDD MIMO receiver can use the information of all codes transmitted through each antenna. Additionally, code reuse can be used across multiple antennas. When MIMO is used, the effective communication code is deteriorated because there may be encoded payloads transmitted in the same code through multiple antennas. Delivering an increased number of midambles using a default midamble allocation scheme or the like may not be practical because it will significantly reduce channel estimation performance. Therefore, it is necessary to have alternative means that the base station can use to communicate to the mobile terminal about which code is valid in the time slot of the multi-antenna transmitter.

The base station may convey resource allocation information by selecting a training sequence as described above. Alternatively, the base station may convey the allocation information of the mobile terminal to the mobile terminal by signaling message, to the mobile terminal set by broadcast information, or by message encoding through a training sequence. The mobile terminal receiver may use the resource allocation information to help decode the signal transmitted by the base station. The mobile terminal can use this information to set up the MUD circuitry to improve detection and decoding performance. If the mobile terminal is familiar with the code assignment of the neighbor cell, the mobile terminal can mitigate intercell interference from the neighbor.

According to some embodiments of the invention, the assignment message directed to the mobile terminal comprises code assignment of another mobile terminal. The base station can instruct the mobile terminal as to which code is assigned. This command may be in the form of an assignment message.

The allocation information may be explicitly included in the allocation message signaled by the base station to the mobile terminal. The allocation information may be in the form of a bitmap or an allocation table. In the case of instructing the code and the time slot assigned to the mobile terminal, the base station may also transmit a similar thing to the indication of the code assignment to the table or other mobile terminal.

According to some embodiments of the present invention, a mobile terminal can monitor allocations directed to other mobile terminals. The mobile terminal can set up an allocation table by decoding an assignment message directed to itself and to another terminal. Thereby, the allocation information is implicitly communicated to the mobile terminal in the cell. The base station may encode the assignment message so that all mobile terminals that have been assigned can decode the effective assignment message to other mobile terminals.

4 shows resource allocation information implicitly delivered to each mobile terminal receiving an assignment. The base station 401 transmits resource allocation information in such a manner that the first mobile terminal MT1 receives and decodes a resource allocation message intended for the MT1 and the second mobile terminal MT2. MT1 may use the allocation information sent to MT2 to mitigate interference due to the signal intended for MT2. Similarly, MT2 may receive and decode resource allocation messages for both MT2 and MT1. MT2 may use the allocation information sent to MT1 to mitigate interference due to the signal intended for MT1.

For the purpose of high speed downlink packet data transmission, UTRA TDD supports High Speed Downlink Packet Access (HSDPA). In particular, HSDPA is suitable for applying MIMO technology. In HSDPA, the base station transmits allocation information to the mobile terminal via a high speed common control channel (HS-SCCH).

5 shows a time and flow chart of HSDPA transmission. HSDPA transmission uses HS-SCCH 501, HS-DSCH 502, and HS-SICH 503 channels. The HS-SCCH 501 conveys allocation information to the mobile terminal. The information is assigned to the mobile terminal and includes an indication of a valid individual HS-DSCH code and time slot. The HS-DSCH 502 carries payload data, such as application data. The HS-SICH 503 conveys the grant status and channel quality indication.

In the conventional UTRA TDD mode system, the HS-SCCH information delivered to the mobile terminal does not include a code assigned to another mobile terminal. Moreover, the assignment message transmitted on the HS-SCCH can only be decoded by the mobile terminal to which the assignment is indicated. The identifier (H-RNTI) of the mobile terminal may be used to scramble the HS-SCCH. In other words, the HS-SCCH is protected by a cyclic redundancy check (CRC) bit masked by the mobile terminal identifier. The CRC bits of the message over the HS-SCCH are encoded by replacing the CRC bits with an exclusive OR of the CRC bits using the identifier of the mobile terminal.

In HSDPA, a mobile terminal determines which code is assigned to another mobile terminal by a conventional midamble processing method such as operated by a default midamble allocation scheme. Therefore, in the conventional system, one mobile terminal cannot decode a message directed to another mobile terminal. In practice, the mobile terminal monitors the HS-SCCH channel set for assignment messages. The mobile terminal masks the CRC received over the HS-SCCH using the identifier (H-RNTI) of the mobile terminal. The CRC test may fail or pass. The CRC test may fail because the HS-SCCH is directed to another mobile terminal, in which case the mask operation will cause the CRC failure. Alternatively, the CRC test may fail because there are so many errors in the HS-SCCH message. If there are too many errors, the HS-SCCH is unreliable and is ignored. If the CRC test fails, the mobile terminal does not decode the HS-SCCH message indicated in the HS-SCCH information. If the CRC test succeeds, the mobile terminal decodes the HS-SCCH information. In either case, the mobile terminal continues to decode other HS-SCCHs within the monitored HS-SCCH set.

According to some embodiments of the present invention, the assignment message includes an identifier of the mobile terminal and a CRC. Neither the assignment message nor the CRC bits are scrambled by the mobile terminal identifier.

6 shows allocation messages 610, 620, 630 for three mobile terminals UE1, UE2 and UE3. The allocation information indicates which code is assigned to the mobile terminal in which time slot. Part of the MIMO allocation information may include an indication for the transmit antenna to which the code is assigned. For example, the MIMO allocation information for UE1 611 may include code allocation for UE1 (eg, codes 3, 4, 5, and 6 through MIMO time slots 5 and 6 at both antennas). MIMO allocation information for UE2 621 may include code allocation for UE2 (eg, codes 10 and 11 in MIMO time slots 6-8) and MIMO allocation information for UE3 631 may be code allocation for UE3. (Eg, codes 1 and 2 in MIMO time slots 5-8 through antenna 2). Each assignment message 610, 620, 630 may also include a mobile terminal identifier 612, 622, 623 and CRC bits 613, 623, 633.

The assignment message directed to the mobile terminal can be sent to the mobile terminal in the start time slot of the frame. This time slot may be a time slot other than MIMO. Allocation information for each mobile terminal can be transmitted on different physical channels in this time slot. For example, in time slot 1, code 1 may convey the assignment for UE1. In time slot 1, code 2 may carry an assignment for UE2. In time slot 1, code 3 may carry an assignment for UE3. The mobile terminal can monitor time slot 1 and determine where the assignment to it has been sent.

The mobile terminal can decode all assignment messages to obtain gain information through all valid assignments in the frame. When the mobile terminal decodes an assignment message including its identifier (UE-IDx), the mobile terminal can set its receiver based on the assignment message. To decode subsequent data bearing assignments, the mobile terminal can set up its receiver to decode the assigned code in a particular time slot. For example, UE2 may decode codes 10 and 11 from antenna 1 through MIMO time slots 6-8. The mobile terminal may set up its receiver with information about all other assignments in the frame (e.g., via MUD circuitry) for improved detection. For example, each mobile terminal can collate code assignment information from all three HS-SCCH assignment messages and infer the following.

In MIMO time slot 5, codes 3-6 are valid at antenna 1 and codes 1-6 are valid at antenna 2;

In MIMO time slot 6, codes 3-6 and 10, 11 are valid at antenna 1 and codes 1-6 are valid at antenna 2;

* In MIMO time slot 7, codes 10-11 are valid for antenna 1 and codes 1-2 are valid for antenna 2,

In MIMO time slot 8, codes 10-11 are valid at antenna 1 and codes 1-2 are valid at antenna 2.

In this way, the mobile terminal can compile the information through all assignments in the frame with the same effect as if the code assignments are known or broadcast as explicit signals.

According to some embodiments of the invention, the base station broadcasts assignment information to the mobile terminal via a broadcast channel.

7 shows a base station 701 delivering allocation information to two mobile terminals. Base station 701 broadcasts message 702 to all mobile terminals that monitor broadcast channels. For example, the base station 701 determines whether to assign a code from one or more time slots to the first mobile terminal MT1. The base station 701 also determines whether to assign a code set from one or more time slots to the second mobile terminal MT2. Base station 701 broadcasts message 702 to all mobile terminals it monitors through the cell. The broadcast message includes allocation information. The allocation information indicates which code is assigned to which time slot and to which antenna. The time slot may be a single source time slot or a MIMO time slot. In the case of MIMO, allocation information includes a set of resources used in each antenna. If the time slot interval begins to have an assigned code, then the base station 701 may not be a MIMO time slot or have a time slot that includes each data payload destined for the mobile terminal with a code assigned for the MIMO time slot. Encode and send

In some embodiments of the present invention, the base station may use a separate broadcast channel to deliver resource allocation information of each mobile terminal to the monitored mobile terminal. In some embodiments of the present invention, the base station broadcasts resource allocation on a channel used to provide cell configuration parameters to the mobile terminal. In UTRA TDD, this may be via system information (SIB) signaling. In this case, the resource allocation may be persistent for multiple frames until SIB signaling is reproduced using the newly defined resource allocation.

8 shows an example of broadcasting resource allocation information in a frame. In this example, there are two transmit antennas, 16 codes per time slot, and 15 time slots, of which four time slots are used for MIMO transmission. In theory, a MIMO time slot using two antennas can carry twice as many codes as non-MIMO time slots through code reuse. MIMO time slots 5 to 8 may include different signals in each antenna. In other words, the data payload in the MIMO time slot transmission through the first antenna may be different from the data payload in the MIMO time slot through the second antenna. Time slots 1 to 4 and 9 to 15 that are not MIMO may transmit the same signal through each antenna. Alternatively, non-MIMO time slots 1-4 and 9-15 may transmit signals through only one or the other antenna.

8 shows a base station for assigning codes to three mobile terminals UE1, UE2 and UE3. The base station has assigned codes 3, 4, 5 and 6 to the first mobile terminal UE1 in both MIMO time slots 5 and 6 via both antennas 1 and 2. The base station assigned codes 11 and 12 to the second mobile terminal UE2 in MIMO time slots 6 to 8 only through antenna 1. The base station assigned codes 1 and 2 to the third mobile terminal UE3 in MIMO time slots 5 to 8 only through antenna 2. The broadcast information is transmitted in codes 15 and 16 at the start of the frame in time slot 1. The broadcast information can be applied to the entire frame. In general, this broadcast information can be transmitted anywhere in the frame. For example, code assignment information for time slot n + 1 may be transmitted in time slot n.

When a mobile terminal is assigned to a code in a time slot, allocation information (or subset of allocation information) for all mobile terminals may be extracted from broadcast allocation information. For example, the base station can broadcast the code assignment information for the MIMO time slot as a bitmap or bit string using codes 15 and 16 of time slot 1. The bitmap may appear as follows.

＊ Time Slot 5: 0011110000000000: 1111110000000000

* Time Slot 6: 0011110000110000: 1111110000000000

＊ Time Slot 7: 0000000000110000: 1100000000000000

* Time slot 8: 0000000000110000: 1100000000000000

In the message described above, "0" indicates that the base station does not transmit payload data with that code, while "1" indicates that a corresponding code is present. The bit string before the colon refers to the code assignment information for antenna 1, and the bit string following the colon refers to the code assignment for antenna 2. It should be understood that there are various ways of encoding broadcast code assignment information. In general, coding other than direct bitmaps may be used. As another example of signaling, the base station may apply compression to the message. Alternatively, the base station may signal the first code and the last code assigned to the time slot at the antenna. By default, the mobile terminal may assume that all codes or codes determined between the first code and the last code may be transmitted or that, by subsequent signal processing means, etc., it may determine which code is transmitted between the first code and the last code. have.

According to some embodiments of the present invention, the base station may signal allocation information to the mobile terminal using a dedicated code or codes. In some embodiments of the invention, the base station uses a separate broadcast channel to transmit code assignment information. The base station may define a specific time slot used for MIMO HSDPA transmission. For example, the base station can broadcast a message in each time slot. The message in the time slot identifies which code is assigned and which code is valid for the MIMO HSDPA time slot. Alternatively, the message in the time slot identifies which code is assigned to the subsequent time slot.

In some embodiments of the present invention, code assignment information may be transmitted via a separate code channel. In UTRA TDD, this code channel may be based on a chip sequence that is not currently used in codes 1-16 of the UTRA TDD signal. This broadcast channel can be modulated using broadcast code assignment information. In some embodiments of the invention, the base station may transmit a separate code channel only in a MIMO time slot. In addition to the 16 codes that a MIMO transmitter can transmit, this separate code channel can also be transmitted.

9 shows a separate code channel transmitted from two antennas, antenna 1 and antenna 2. FIG. Alternatively, only a single separate code channel is transmitted. In other words, the same split code channel is transmitted from two antennas, antenna 1 and antenna 2.

According to some embodiments of the invention, the base station transmits allocation information during the training sequence. The split code channel discussed above does not need to extend all the time slots. For example, a separate code channel may exist only during the midamble portion of the data burst.

The separate code channel may be transmitted identically from each antenna. Alternatively, different versions of the same information can be transmitted from each antenna. This provides a diversity class that can improve system performance. For example, where a separate code channel is transmitted only during the midamble portion of a data burst, the burst structure is used when there are two transmit antennas that may contain a midamble sequence using codes in different orders. do.

FIG. 10 shows a separate code channel transmitted from two antennas, antenna 1 and antenna 2. FIG. When transmitted over antenna 1, the separate code channel transmits code assignment information for two antennas, antenna 1 and antenna 2. Similarly, when transmitted over antenna 2, the separate code channel transmits code assignment information for two antennas, antenna 1 and antenna 2. The separate code channel at antenna 1 is configured to convey code assignment information for antenna 2, followed by code assignment information for antenna 1. The separate code channel at antenna 2 is configured to convey code assignment information for antenna 1, followed by code assignment information for antenna 2. By transmitting code allocation information through two antennas, antenna 1 and antenna 2, antenna diversity gain can be realized. By changing the configuration of the separate code channel in each antenna, the time diversity gain can be realized.

A base station having four antennas may transmit code allocation information for antennas 2 to 4 following the first antenna code allocation information for antenna 1. FIG. The second antenna may be used to transmit the code assignment information for antenna 2, followed by the code assignment information for antennas 3, 4 and 1. The third antenna may be used to transmit the code assignment information for antenna 3, followed by the code assignment information for antennas 4, 1 and 2. The fourth antenna may be used to transmit code allocation information for antennas 1 to 3 following the code allocation information for antenna 4.

In some embodiments of the invention, allocation information regarding the data bearing time slots may be transmitted by the base station in the time slots preceding the data bearing time slots.

Signaling or broadcasting of allocation information may occur aperiodically or periodically. For example, in some embodiments, broadcast channel transmission occurs when there is a change in code and time slot allocation. When a new resource is allocated or released, the broadcast channel may signal updated resource allocation information. In some embodiments, when the mobile terminal requests for information, current resource allocation information is passed to the mobile terminal.

In another embodiment, the broadcast channel may be periodic. For example, a broadcast channel may occur once per frame. The broadcast channel may broadcast resource allocation information at the start of the frame and may include information about each related time slot in the frame. In another embodiment, a broadcast channel occurs once per effective time slot. The broadcast channel may broadcast resource allocation information for each valid time slot based on the time slot. The broadcast channel may broadcast allocation information on the current frame or time slot. Alternatively, the broadcast channel may broadcast allocation information for subsequent frames or time slots.

In some embodiments of the present invention, the allocation information transmitted by the base station may include both allocation information for resources in the cell where the terminal is located and allocation information for resource allocation in the neighboring cell. In some embodiments of the present invention, the base station may transmit a broadcast message including resource allocation information for neighboring cells. For example, some of the broadcast messages may apply to resource allocation in the current cell and other broadcast messages may apply to resource allocation in neighboring or neighboring cells.

The broadcast feature of broadcast resource allocation signaling can be applied by a base station that ensures that all mobile terminals that can use the information can receive and decode all assignment messages.

In some embodiments of the present invention, the base station signals or broadcasts resource allocation information for each mobile terminal to all valid mobile terminals in the cell. Assignment information may be sent to individual mobile terminals or to individual groups of mobile terminals or broadcast to all mobile terminals or categories of mobile terminals.

In some embodiments of the invention, the base station may broadcast information to a subset of mobile terminals in the cell. For example, if the base station determines that only a subset of terminals in the cell will benefit from broadcast resource allocation information, the base station broadcasts only to these mobile terminals. In some embodiments, the base station transmits a signal message or broadcast at a power level sufficient for all assigned mobile terminals to receive.

For example, HS-SCCH is typically power controlled by a base station. The base station fully utilizes the level of transmit power in the HS-SCCH to allow the mobile terminal to which the HS-SCCH message is directed and successfully decode the HS-SCCH message.

In some embodiments of the present invention, allocation information may be transmitted at a sufficient power level only in the mobile terminal interested in decoding. For example, some mobile terminals may require the base station to transmit signals at a higher power level than other mobile terminals. If all mobile terminals with allocated resources require less signal power than the group of remote mobile terminals, the base station can set a power level that allows the mobile terminal with allocated resources to receive an assignment message, but the power level is far. Cannot be high enough to receive. In other words, the base station can broadcast the allocation information at a power level sufficient for the mobile terminal with the allocated resources to receive. The base station cannot use the power level required to reach all terminals in the cell.

In some embodiments of the present invention, the base station may apply a level of power to a broadcast that includes code assignment information sufficient to allow a group of mobile terminals to decode the broadcast code assignment information. For example, the downlink transmission power levels required to receive code assignment information by five mobile terminals in a cell are +10 dBm, + for mobile terminals UEl, UE 2, UE 3, UE 4, and UE 5, respectively. 15 dBm, +12 dBm, +20 dBm, and +8 dBm, and if only UEl, UE 2, and UE 3 codes have been assigned in the frame, the base station is required for UEl, UE 2, and UE 3 to receive code assignment information. We will use the maximum power downlink transmit power level of +15 dBm.

In some embodiments of the present invention, the base station may transmit the code assignment message at a sufficient power level only to the mobile terminal receiving the message to decode all assignment messages transmitted in the cell. For example, the downlink transmission power required to transmit code allocation information to five mobile terminals in a cell is +10 dBm, +15 dBm, +12 dBm, + for UE1, UE2, UE3, UE4, and UE5, respectively. 20 dBm and +8 dBm, and if only codes UE1, UE2 and UE3 are assigned in the frame, then the base station will assign +15 dBm to assign a message to UE1, +15 dBm to assign a message to UE2, and to assign a message to UE3. A downlink transmit power of +15 dBm can be applied. Conventionally, powers of +10 dBm, +15 dBm and +12 dBm have been applied to each allocation message, respectively, but this power allocation does not allow UE2 to successfully derive the full allocation information for all mobile terminals in the cell. Do not.

Although the invention has been described in terms of particular embodiments and illustrative figures, those skilled in the art will recognize that the invention is not limited to the embodiments and figures described. For example, many of the embodiments described above refer to a transmitter at a base station and a receiver at a mobile terminal. In another embodiment, the transmitter is at the mobile terminal and the receiver is at the base station. In addition, many embodiments describe or include midambles. In other embodiments, preamble or postamble training sequences are used.

The drawings provided are only illustrative and need not be drawn to scale in and out. Although other parts in the figure are reduced, the size of certain parts can be emphasized. The drawings are intended to illustrate various implementations of the invention that can be understood and appropriately carried out by those skilled in the art.

Claims (28)

A base station comprising at least a first and a second antenna, for communicating data for a first mobile terminal in a cellular wireless network, Means for determining a first set of time slots of time slots for allocating to the first mobile terminal for use in receiving data transmitted from the base station to the first mobile terminal; Assign one or more time slots from the first set of time slots to the first antenna, assign one or more time slots from the first set of time slots to the second antenna, or from the first set of time slots Means for assigning at least one time slot of to both the first and second antennas, Means for generating a message providing an indication as to which time slot in the first set of time slots has been assigned to the first mobile terminal, wherein the generated message is adapted to replace the time slot from the first set of time slots; Instructions for assigning to either or both of the first and second antennas; Means for sending the message to the first mobile terminal Base station comprising a. The method of claim 1, Means for determining a second set of time slots of at least one time slot for allocating to the second mobile terminal for use in the second mobile terminal in receiving data transmitted from the base station to a second mobile terminal; Include, The message generated by the means for generating the message includes an indication of the allocation of the second set of time slots to the second mobile terminal, And the means for transmitting is configured to send the message to the second mobile terminal. The method of claim 1, The means for assigning assigns one or more time slots from the second set of time slots to the first antenna and assigns the remaining time slots of the second set of time slots to the second antenna, or the second Assign one or more time slots from a set of time slots to both the first and second antennas, The message generated by the means for generating the message includes an indication of the allocation of time slots from the second set of time slots for either or both of the first and second antennas. The method of claim 1, Means for transmitting data for the first mobile terminal over a high speed downlink packet access (HSDPA) channel using the first set of time slots. The method of claim 1, Means for transmitting data for the first mobile terminal over a high speed downlink packet access (HSDPA) channel using the first set of time slots, And the first mobile terminal is capable of forming an HSDPA-multi-input / output (MIMO) channel by receiving data transmitted from the first and second antennas of the base station using a plurality of receive antennas. 3. The method of claim 2, The means for transmitting comprises means for transmitting the message on a control channel monitored by the first and second mobile terminals. The method of claim 6, The control channel is a fast shared control channel. 3. The method of claim 2, The means for transmitting comprises means for transmitting the message on a broadcast channel monitored by the first and second mobile terminals. 9. The method of claim 8, The broadcast channel is a high speed downlink shared channel. The method according to any one of claims 1 to 9, Means for transmitting, Means for determining a power level such that the first and second mobile terminals receive the message; Means for transmitting the message on a broadcast channel at the determined power level. The method according to any one of claims 2 to 9, The message providing indicating an allocation table providing an indication of the allocation of the first and second time slots to the first and second mobile terminals. 12. The method of claim 11, The allocation table indicates an allocation of the time slots from the first and second time slot sets for the first and second antennas of the base station for transmitting data for the first and second mobile terminals. To provide a base station. The method of claim 1, The means for determining is configured to determine, in receiving data transmitted from the base station to a first mobile terminal, a first set of codes to be assigned to the first mobile terminal for use in the first mobile terminal; , The means for assigning allocates one or more codes from the first code set for the first antenna and the remaining codes from the first code set for the second antenna, or the first and Assign at least one code from the first code set to all of the second antennas, The message generated by the means for generating the message includes an indication of the first code set and the first time slot set assigned to the first mobile terminal and one of the first and second antennas or Providing an indication of allocation of code and time slots from the first set of codes and the first set of time slots for all. The method of claim 1, And the data transmitted to the first mobile terminal comprises a training sequence. A method of communicating data from a base station comprising at least first and second antennas to a first mobile terminal in a cellular wireless network, the method comprising: When receiving data transmitted from the base station to the first mobile terminal, determining a first set of time slots for allocating to the first mobile terminal; Allocating one or more time slots from the first set of time slots for the first antenna, allocating one or more time slots from the first set of time slots for the second antenna, or the first and first Allocating at least one time slot from the first set of time slots for both antennas, Providing a message providing an indication of which one of the first set of time slots has been allocated to the first mobile terminal, wherein the generated message is configured to retrieve the time slot from the first set of time slots; Instructions for assigning to either or both of the first and second antennas; Transmitting the message to the first mobile terminal Data communication method comprising a. 16. The method of claim 15, In receiving data transmitted from the base station to a second mobile terminal, determining a second set of time slots of one or more time slots for allocation to the second mobile terminal for use in the second mobile terminal. , The generated message includes an indication of the allocation of the second set of time slots to the second mobile terminal, And the transmitting step transmits the message to the second mobile terminal. 16. The method of claim 15, The allocating may include allocating one or more time slots from the second set of time slots to the first antenna and allocating the remaining time slots of the second set of time slots to the second antenna, or the second time. Assign one or more time slots from a set of slots to both the first and second antennas, The generated message includes an indication of allocation of time slots from the second set of time slots for either or both of the first and second antennas. 16. The method of claim 15, Using the first set of time slots, transmitting data for the first mobile terminal over a high speed downlink packet access (HSDPA) channel. 16. The method of claim 15, Using the first set of time slots, transmitting data for the first mobile terminal over a high speed downlink packet access (HSDPA) channel, And the first mobile terminal is capable of forming an HSDPA-multi-input / output (MIMO) channel by receiving data transmitted from the first and second antennas of the base station using a plurality of receive antennas. 17. The method of claim 16, And the transmitting comprises transmitting the message on a control channel monitored by the first and second mobile terminals. 21. The method of claim 20, And the control channel is a high speed shared control channel. 17. The method of claim 16, And the transmitting comprises transmitting the message on a broadcast channel monitored by the first and second mobile terminals. 23. The method of claim 22, And the broadcast channel is a high speed downlink shared channel. The method according to any one of claims 15 to 23, The transmitting step, Determining a power level for the first and second mobile terminals to receive the message; Transmitting the message on a broadcast channel at the determined power level. The method according to any one of claims 16 to 23, wherein And wherein said message is indicative of an assignment table providing an indication of allocation of said first and second time slots to said first and second mobile terminals. 26. The method of claim 25, The allocation table indicates an allocation of the time slots from the first and second time slot sets for the first and second antennas of the base station for transmitting data for the first and second mobile terminals. Providing a data communication method. 16. The method of claim 15, The determining step is configured to, when receiving data transmitted from the base station to the first mobile terminal, determine a first set of codes to be assigned to the first mobile terminal for use in the first mobile terminal, The assigning may include allocating one or more codes from the first code set for the first antenna and allocating the remaining codes from the first code set for the second antenna, or the first and the first codes. Assign at least one code from the first code set for both antennas, The generated message includes an indication of the first code set and the first time slot set assigned to the first mobile terminal, the first code set for one or both of the first and second antennas, and Providing an indication of the allocation of code and time slots from the first set of time slots. 16. The method of claim 15, And the data transmitted to the first mobile terminal comprises a training sequence.

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